In getting my studio set up after a 40 year detour, I did not want to spend a huge amount of money. I began making all varieties of things myself. It turned out to be much simpler, easier than I initially anticipated. Three of my projects ended up being published in ceramics journals. They are attached to comments to this topic. I also have a number of other projects for which I have not not been written up for publication that I will be adding as comments to this topic.  I invite others to add descriptions of their projects to this topic.

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That's a great idea for grinding greenware. you probably need to fasten it in some way so you can easily empty out the grinding refuse. Otherwise it is going to load up quickly and stop sanding.

I'm not sure if this stuff is tough enough to deal with bisque or glaze fired pots. if you grinding bisque or glaze fired look further up in this discussion to April 3 when I posted how to make bottom grinder suitable for bisque or glaze fired stuff.

Only green ware, should be no issue. I think that a strong brush can remove the clay or just water, the letting it dry afterwards.
There was a time that I saw glass blower guy using a round disk with diamond particles glued in it.He grind the bottom of he's blown glass project on it.

heat kills diamonds very quickly. So if you do any grinding with diamonds make sure you flush the surface with lots of water while you're grinding

Cheapskate Spray Booth

When I put my electric kiln in the basement, discovered that it put out enough fumes to give me a headache when firing. So a kiln vent was in order. I decided the commercial units were too expensive for what they are made from so I opted to build my own. The little 4" duct fan I purchased didn't develop enough suction to reverse the bottom to top heat flow in my kiln.

So I got a powerful Vortek 4" fan that has excess drawing power.

That could have been the end of the story, but when I saw what Steven Hill was doing by spraying glazes, I knew I had to have a spray booth. Again being the cheapskate that I am, I was horrified by the prices of spray booths. It occurred to me that if my booth had a small enough opening, I might be able to use my kiln vent fan to vent the spray booth. I was thinking of building the box out of wood, but decided to look for alternatives. Steven's booth was built from a fiberglas shower stall. Off I went to Home Depot in search of the perfect spray booth. I ended up getting the biggest Rubbermaid plastic storage box I could find.

I cut out one end of it and cut a 4" hole in the other end, and added a 4" duct adaptor. I just sit the thing upside down on top of my kiln an connect it to my vent and it makes a serviceable spray booth. I buy cheap furnace filters, cut them in half and layer 3 of them in front of the exhaust to trap as much glaze overspray as possible.

My setup is a little small but quite useable. It captures most of the overspray, except when spraying a hollow form like the inside of a bowl that sends the spray back at me with enough velocity to overcome the fan's draw, but I wear a respirator when spraying, so it's not that big a problem. I've done three spraying sessions and am pretty happy with my setup. -George Lewter-

Update Feb. 8, 2112

What I have allows me to spray glazes and contain almost all of the overspray. I go through a fair amount of furnace filters and the glaze in the filters is wasted.

800-1,000 cfm is the recommended air movement for spray booths.  Mine is only 160 cfm, serviceable, but not a strong intake - go higher if possible with 6-8" vent piping. Its what I had already in use for my kiln vent.  More air movement is better.

I plan to replace the plastic box with the tub from an old dishwasher for better size and easier cleaning. The bottom half of a broken 36" fiberglass shower is also a good choice. Plumbing supply places frequently have them that have been damaged in shipment. The air outlet will be at the top. It will also work better if I get around to a water bath system which would spray water down the walls and into a reservoir with a recirculating pump. The glaze would settle to the bottom and clearer water nearer the top would be drawn up to again for spraying down the walls. This would capture most overspray and keep the  used glaze for recycling into scrap glaze.

Comment by Kathy Ransom on May 27, 2014 at 11:10am

I've made a few spray booths and spent a lot of time searching the internet for ideas to make a really good spray booth!  The clean-up is huge and there are problems such as spray blowing back and settling on surfaces in my studio that are frustrating.  I don't have the talent to build this booth but I'm hoping my husband does and can build me this booth someday  This booth looks terrific but the instructions aren't quite as clear and it would take more know how to complete A few more tutorials are

Comment by George Lewter on May 27, 2014 at 12:53am

The best booths in my opinion are the ones where the booth walls are being washed down by a stream of water that collects in a reservoir with particulates settling out and clearer water near the top being drawn into a water pump to repeat the process. Getting a cascade of flowing water down all the walls is the hard part. I haven't tried it.

My latest modification is to stagger rectangular plastic plates in front of the filters. They catch most of the spray, the filters catch more. This is totally a guess, but I think less than 1% gets drawn out by the fan. I don't notice any glaze on the concrete patio 8" below my fan outlet. Any spray setup entails a lot of cleanup.

Comment by Rodney Allen Roe on May 26, 2014 at 9:10am

I'm new here and just found this very interesting article.  My kiln is in a large open garage with a window next to the kiln so I vent into the open air.  However, I would like to build something like this.  How much glaze gets past the furnace filters?  I was thinking of venting out the open window where it would fall onto shrubbery below.  Can you vent through a water reservoir like the base of a shop vac to catch glaze that gets through.  I don't want to have a mess on the shrubs.

Comment by George Lewter on April 17, 2014 at 4:15pm

A better fan for a spray booth would be the Tjernlund M-6 Inline Duct Booster Fan 6" 530 CFM

It moves much more air and is less expensive than the 4" fan I used. A by-pass inlet could be used on a combination spray booth / kiln vent installation to reduce suction when venting the kiln.
Comment by Kathy Ransom on December 14, 2010 at 1:59pm

Thank you very much for the info George.  I hope to have my kiln set up and commence firing very soon!

Comment by Robert Seele on December 13, 2010 at 3:17pm

Here is a link for another home made spray booth.

Comment by susan claysmith on December 7, 2010 at 9:04pm
Hi George - I agree that the shop vac will probably be inadequate. I do like your blower system setup and I think that I will check into something with more power when I set up my system. How often do yo need to change your filters? Have you tried washable filters? susan
Comment by George Lewter on December 7, 2010 at 8:41pm
Susan and Kathy.
First to Susan -- Your shop vac will be better than no vent at all, but that high velocity air moving into the hose is many time faster than what you will get at the large front opening of your laundry tub. I think you will experience a lot of blow back of overspray that will escape the spray booth. Professional grade spray booths move in the vicinity of 1000 cu ft per minute, mine probably moves 150 and I get a bit of blow back off some shapes. I think you will have even more. If you already have the shop vac go ahead and try it. The worst that can happen is it won't draw enough volume to be effective, in which case you will need to go to a bigger fan and larger vent piping. Make sure you wear a dust and mists rated respirator when spraying. If your getting a lot of blow back you will find glaze dust on the outside of your respirator, on you glasses if you wear them, and on your face after a spraying session. These are obvious signs that your spray booth isn't drawing in enough air.

Kathy, You need a galvanized steel box with flanges that you can screw with sheet metal screws to the bottom of your kiln. 99% of the air moving through your vent will be room temperature air that will rapidly mix with the 1% of 2000 degree air coming from inside your kiln. Except for the flange screwed to the kiln, none of the vent piping will be more than slightly warm to the touch. I have posted a much more complete description of my kiln vent on a separate web page I describe a shutter in the vent box that lets a lot of room air mix with the hot kiln air so it can easily be handled by standard furnace and air conditioning vent piping.
Comment by Kathy Ransom on December 7, 2010 at 7:29pm
I have been trying to put together a down draft vent for a while but when I go to home depot and tell the salesmen what I want to build and the temp the kiln will reach I always get "you can't do that!" I have an in-line fan but my biggest problem is the collector box and a spring mechanism to hold the box tight to the bottom of the kiln. The boxes I've found are either PVC or aluminum and need to be glued together but I'm not sure if either will hold/melt. Can you tell me what you use to hold the box against the bottom of the kiln when it contracts during firing George?
Comment by susan claysmith on December 3, 2010 at 6:03pm
I have been thinking about building a spray booth. I like what you've done here. I was thinking that I would get a single plastic laundry tub and put it on edge and running a wet/dry shop vac off of the drain, which could be exhausted outside. I think that your venting and filtrarion system is a better way to go, although I think the laundrry tub might be a good way to go for the hood because of the size. I would enlarge the drain area to fit 4 inch venting to it. Any thoughts on this idea?
Comment by Marv Kitshaw on October 8, 2010 at 4:49am
I think we could also learn a lot from space saving for this too!
Comment by JUDITH FREDERICK on July 25, 2010 at 9:49pm
I am interested in you kiln vent, would you care to share a little more about that. I would appreciate it.
Comment by Judy Thompson on July 6, 2010 at 11:49pm

I am going to have my S.O. to look at this. What a great idea!
Comment by George Lewter on January 3, 2010 at 3:17pm

I would not use a speed controller. They are quite twitchy about maintaining a constant speed over time. The cycling of the A/C power voltage curve helps a motor keep a constant speed. I wouldn't buy the Vortek fan at this point unless you want to do the kiln vent/spray booth combo. I think by dampering the holes at the "cup", you will solve your venting issue. $115 sounds like about what I paid for the vortek fan. I don't really have to, but I usually open a small basement ventilating window for make up air the kiln keeps the basement pretty toasty, so I'm not pulling cold air into the house somewhere else where I don't really want it coming in.
Comment by George Lewter on January 3, 2010 at 1:54pm
Good questions. On my overpowered fan system I have a single 3/8" hole in the lid of the kiln and four 1/4" holes in a 6" square pattern at the bottom that fit inside a sheetmetal box with a four inch duct adaptor at the back and an adjustable shutter at the front. I quickly discovered that the shutter could not open far enough to reduce the suction to the point that hot air was coming out of the top of the kiln. As my kiln consistently fired cooler at the top, I concluded that I was pulling in too much air via the kiln vent, so I opened another shuttered opening in the 4" duct line between the kiln and the fan, and by adjusting the air there, I was able to finely control the exhaust/suction at the top of the kiln. I found the same situation you described -- a suction setting that is just barely pulling air at the top at low temperatures at the beginning of the firing cycle is not strong enough at high temperatures to maintain the top to bottom air flow. Your idea of closing off holes at the bottom is the right one, but you need to do it in a way that is adjustable, so you can change it during the firing and as the fan ages and loses some of its efficiency.
Comment by eleanor akowitz on December 24, 2009 at 4:49pm
wow! that is neat and cheap. my only concern is overspray on my kiln sides and on the walls by the kiln. is suppose i could do this by buying a vortex fan and adapting it to a home depot box. and move it away from the kiln . great idea!

Re: Cheapskate Spray Booth

If you just want a spray booth (as opposed to a kiln vent/spray booth combo), I have found a couple of dust collector systems at Harbor Freight that should work better than the vortex fan that I have been using.  Both move a lot more air (600 to 900 CFM) and can be stowed away, rather than being part of a permanent vent system.  Both appear to be pretty noisy as well, and would be best placed outside your studio, but as close to the spray booth as possible. Is available in store only and was sale priced at $60 regular price $80

This second unit is larger and more powerful. It looks like they will ship it if you want to buy online. 

On sale it is $130 regularly $140 

With any spray booth system, you need to collect as much dust as possible in the booth itself, either with filters and baffles, or a water bath running down the walls. Any remaining dust should be piped outside of the building. DO NOT DEPEND ON THE BAGS SHOWN HERE TO CAPTURE SILICA AND TOXIC METAL OXIDES. They won't work and they will quickly clog, stopping the air flow through the spray booth.  

This is a great wealth of info for everyone. Thank you so much for posting it all here. I've had hit and miss DIY equipment. A total fail at a slab roller attempt. Pottery Making Illustrated ran an article about a DIY slab roller and It looked strong enough so I gave it a go. Despite everything I could do to strengthen the bar and roller. The clay always flexed it. No matter how much I prepped my "to be" slabs... no matter how much I reinforced my roller. Be wary of these ABS and PVC slab rollers. Clay is mightier. I will definitely be creating some sort of vent in my new studio space. This is a great starting place for it.

Thanks again!

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